Made for high mileage runners and worn by Team NB athlete and DMR Indoor World Record Holder, Sarah Brown, the 880v5 is well cushioned to help you outlast the long run.12 mm drop: due to variances created during the development and manufacturing processes, all references to 12 mm drop are approximateAsymmetrical heel counterBlown rubber outsoleBreathable air meshSynthetic/mesh upperStyle W880SB5 is approved Medicare/HCPCS code = A5500, and may be eligible for Medicare reimbursement.